Liquid crystal display device

ABSTRACT

A liquid crystal display device ( 100 ) includes a TFT substrate ( 110 ) including a TFT ( 10 ), an interlayer insulating layer which covers the TFT ( 10 ), a pixel electrode ( 12 ) electrically connected to the TFT ( 10 ) via a contact hole ( 14 ) formed in the interlayer insulating layer, a storage capacitor bus line ( 6 ) and a storage capacitor electrode ( 8 ) connected to the storage capacitor bus line ( 6 ), and a storage capacitor counter electrode ( 16 ) having a light-shielding property electrically connected to the TFT ( 10 ) and the pixel electrode ( 12 ), the storage capacitor counter electrode ( 16 ) constituting a storage capacitor portion together with the storage capacitor electrode ( 8 ) with an insulating layer interposed therebetween. The liquid crystal display device ( 100 ) also includes a counter substrate ( 120 ) including a counter electrode. Between the TFT substrate ( 110 ) and the counter substrate ( 120 ), a columnar spacer ( 24 ) is disposed in a center portion of a pixel region so as to at least partially overlap with the storage capacitor counter electrode. The contact hole ( 14 ) is provided so as to overlap with the storage capacitor counter electrode ( 16 ). A black matrix ( 20 ) includes a portion ( 20   x ) which integrally covers the TFT ( 10 ) and the columnar spacer ( 24 ).

TECHNICAL FIELD

The present invention relates to a liquid crystal display device whichoperates in a VA mode.

BACKGROUND ART

As a display device such as a display device of a thin-screen televisionor a personal computer, or a small display device for a cellular phoneor a smart phone, an active matrix liquid crystal display device whichuses a thin film transistor (TFT: Thin Film Transistor) as a switchingelement is widely utilized. In addition to conventional TN liquidcrystal display devices, other types of liquid crystal display devicessuch as liquid crystal display devices utilizing a VA (VerticalAlignment) mode as a vertical alignment mode or an IPS(In-Plane-Switching) mode as a horizontal electric field mode have beendeveloped.

As a liquid crystal display device of VA mode, a liquid crystal displaydevice of MVA (Multi-domain Vertical Alignment) mode, a liquid crystaldisplay device of CPA (Continuous Pinwheel Alignment) mode, and the likeare known. In the liquid crystal display device of MVA mode, multipledomains in which orientation directions of liquid crystal molecules aremutually different are formed in one pixel. In the liquid crystaldisplay device of CPA mode, orientation directions of liquid crystalmolecules are continuously varied around a rivet or the like formed onan electrode in the center portion of a pixel.

For example, Patent Document No. 1 describes a liquid crystal displaydevice comprising a plurality of projecting structures in a pixel regionand operating in a VA mode. The projecting structures disposed in thepixel region are utilized for regulating the orientation of liquidcrystal molecules. Part of the projecting structure also functions as acolumnar spacer used for maintaining a cell gap (the thickness of aliquid crystal layer).

Patent Document No. 2 describes a liquid crystal display device of MVAmode in which many minute slits (cuts) extending in directions ofazimuth angles of 45°, 135°, 225°, and 315° are formed in a pixelelectrode (also referred to as a comb-like pixel electrode or afishbone-shaped pixel electrode). The azimuth angles are angles measuredby regarding the three o'clock direction as 0° and regarding theanti-clockwise direction as a direction of positive angles. The liquidcrystal molecules are aligned in parallel to these slits, therebyrealizing four-divided domain structure. Patent Document No. 3 describesa semi-transmissive liquid crystal display device which can operate inthe MVA mode.

CITATION LIST Patent Literature

-   Patent Document No. 1: Japanese Laid-Open Patent Publication No.    2005-309239-   Patent Document No. 2: International Publication No. WO 2009/154031-   Patent Document No. 3: Japanese Laid-Open Patent Publication No.    2009-69331

SUMMARY OF INVENTION Technical Problem

Patent Document No. 1 discloses a configuration with a projectionstructure functioning as a columnar spacer, the projection structurebeing disposed in a region in which a storage capacitor (also referredto as an auxiliary capacitor) is formed in the center portion of apixel. The document also discloses a configuration in which a BM (blackmatrix) is provided on a counter substrate in a position correspondingto the columnar spacer. However, a liquid crystal display deviceincludes a portion in which alignment disorder may occur such as acontact hole in addition to the columnar spacer. For this reason, thedisplay quality may sometimes be degraded only by providing the BMseparately with respect to the columnar spacer. In the configuration inwhich respective regions to be light-shielded in the pixel region (e.g.contact holes or TFTs) are dispersedly disposed, especially, it issometimes difficult to increase the aperture ratio in the small-sizedand high-definition liquid crystal display device.

The embodiment of Patent Document No. 2 describes a configuration inwhich a contact hole is provided in the vicinity of a switching device(TFT), and a region including the TFT and the contact hole is integrallycovered with a BM on a counter substrate. However, the liquid crystaldisplay device disclosed in Patent Document No. 2 is configured in sucha manner that the columnar spacer is provided in a position which doesnot overlap with the pixel electrode (e.g. four corners of a pixel).

Patent Document No. 3 describes a configuration in which an auxiliarycapacitor portion is formed by using a drain electrode and an auxiliarycapacitor line in the vicinity of a TFT, and a contact hole is providedon the auxiliary capacitor, thereby electrically conducting the pixelelectrode and the drain electrode. In this liquid crystal displaydevice, however, since a columnar spacer is disposed in the vicinity ofthe boundary between a reflecting electrode and a transmission electrodein adjacent two pixels, the spacer is not disposed in the pixel region.

In the liquid crystal display devices described in Patent Document No. 2and Patent Document No. 3, regions to be preferably light-shielded aredisposed proximately, so that an increase in aperture ratio can beexpected. In the case where the pixel size is relatively larger, theconfiguration in which the columnar spacer is not disposed in the pixelregion has a small influence on the aperture ratio, even if a space forthe columnar space can be ensured on the outside of the pixel electrodewithout affecting display. In the case of high definition and a smallpixel size, it is sometimes difficult to provide a columnar spacer onthe outside of the pixel region without affecting display and withoutreducing the aperture ratio.

In a liquid crystal display device which operates in CPA mode, or in aliquid crystal display device of VA mode which utilizes afishbone-shaped pixel electrode, for example, a columnar spacer whichalso functions as an orientation regulating structure is sometimesprovided in the center portion of a pixel region. In such a case, indisplaying a black image, by means of a vertical alignment film on thecolumnar spacer, the orientation of liquid crystal molecules in thevicinity thereof is regulated. With such a configuration, if alight-shielding member is not disposed for the columnar spacer, thecontrast ratio is degraded because of light leakage or the like. On theother hand, if a light-shielding member is disposed for the columnarspacer, the reduction of pixel aperture ratio (the reduction ofluminance) is inevitably caused.

Particularly in a small-sized and high-definition liquid crystal displaydevice (a device with small dot pitch), the minimum line width isdefined by design rules (process rules), so that the ratio of occupationarea of lines to the pixel area has a tendency to increase. For thisreason, in the case where lines having light-shielding property areused, such lines may be a hindrance factor in increasing the apertureratio or in promoting the miniaturization and high definition.Accordingly, particularly in the high-definition liquid crystal displaydevice in which lines having light-shielding property are used forforming storage capacitors or the like, it has been desired that theaperture ratio should be more improved. Small-sized and high-definitiondisplay devices are utilized in electronic books, smart phones, and thelike, and the demand thereof is further anticipated from now on.

The present invention has been conducted in order to solve theabove-mentioned problems, and the objective thereof is to provide aliquid crystal display device which performs bright display with animproved contrast ratio by appropriately disposing a light-shieldingregion.

Solution to Problem

The liquid crystal display device according to an embodiment of thepresent invention is a liquid crystal display device including: a TFTsubstrate, a counter substrate, and a vertical alignment type liquidcrystal layer sandwiched between the TFT substrate and the countersubstrate, wherein the TFT substrate includes: a first substrate; a gatebus line provided so as to extend along a first direction on the firstsubstrate; a source bus line provided so as to extend along a seconddirection which intersects the first direction on the first substrate; aTFT provided in the vicinity of the intersecting portion of the gate busline and the source bus line; an interlayer insulating layer whichcovers the TFT; a pixel electrode electrically connected to the TFT viaa contact hole formed in the interlayer insulating layer; a storagecapacitor bus line provided on the first substrate and a storagecapacitor electrode connected to the storage capacitor bus line; and astorage capacitor counter electrode having a light-shielding propertyelectrically connected to the TFT and the pixel electrode, the storagecapacitor counter electrode constituting a storage capacitor portiontogether with the storage capacitor electrode with an insulating layerinterposed therebetween, and the counter substrate includes: a secondsubstrate; and a counter electrode provided on the second substrate, andwherein the liquid crystal display device further comprises a blackmatrix having a light-shielding property provided on the first substrateor on the second substrate, and a columnar spacer provided between theTFT substrate and the counter substrate, the columnar spacer beingdisposed in a center portion of a pixel region corresponding to thepixel electrode so as to at least partially overlap with the storagecapacitor counter electrode, the contact hole being provided so as tooverlap with the storage capacitor counter electrode, and the blackmatrix including a portion which integrally covers the TFT and thecolumnar spacer.

In one embodiment, the source bus line is disposed so as to extend alonga peripheral portion of the pixel region, and the TFT is disposed in thevicinity of the peripheral portion of the pixel region.

In one embodiment, the columnar spacer is disposed so as to at leastpartially overlap with the pixel electrode.

In one embodiment, the black matrix is disposed so as to at leastpartially overlap with the storage capacitor counter electrode.

In one embodiment, the black matrix includes a first BM portion forlight-shielding the TFT and a second BM portion for light-shielding thecolumnar spacer, the first BM portion overlapping with the second BMportion.

In one embodiment, the contact hole and the columnar spacer are disposedso as to at least partially overlap with each other.

In one embodiment, the orientation of liquid crystal molecules of theliquid crystal layer is radially regulated by the columnar spacer when avoltage is applied.

In one embodiment, the pixel electrode includes a plurality of firstminute electrodes extending in a third direction, a plurality of secondminute electrodes extending in a fourth direction, a plurality of thirdminute electrodes extending in a fifth direction, and a plurality offourth minute electrodes extending in a sixth direction, the thirddirection, the fourth direction, the fifth direction, and the sixthdirection being mutually different.

In one embodiment, the pixel electrode includes a backbone portionformed in a boundary portion of the first to fourth minute electrodes,and an additional storage capacitor is formed in a region correspondingto the backbone portion.

In one embodiment, the liquid crystal display device includes aplurality of pixel regions, and a projection structure which is lowerthan the columnar spacer is provided in the center portion of a pixelregion which is different from the pixel region in which the columnarspacer is provided among the plurality of pixel regions.

In one embodiment, the liquid crystal display device further includes asub pixel electrode disposed adjacently to the pixel electrode, andconnected to the TFT via a capacitance coupling.

In one embodiment, the liquid crystal display device includes aplurality of pixel regions, and the position of the contact hole withrespect to the columnar spacer is different between at least two pixelregions among the plurality of pixel regions.

Advantageous Effects of Invention

According to the embodiments of the present invention, it is possible toimprove the display characteristics of a vertical alignment type liquidcrystal display device which operates in a VA mode.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view showing the configuration of a liquid crystaldisplay device according to Embodiment 1 of the present invention, inwhich (a) emphatically shows the components on a TFT substrate, and (b)emphatically shows the components on a counter substrate.

FIGS. 2 (a) and (b) are enlarged views showing the center portion of apixel in FIG. 1( a).

FIG. 3 is a plan view showing the configuration of a liquid crystaldisplay device according to a modified embodiment of Embodiment 1, inwhich (a) emphatically shows a TFT and a storage capacitor portion on aTFT substrate, and (b) emphatically shows a BM on a counter substrate.

FIG. 4 is a plan view showing the configuration of a liquid crystaldisplay device in a modified embodiment of Embodiment 1, and showing thecase of a smaller pixel size.

FIG. 5 is a plan view showing the configuration of a liquid crystaldisplay device according to Embodiment 2 of the present invention, inwhich (a) emphatically shows the components on a TFT substrate, and (b)emphatically shows the components on a counter substrate.

FIG. 6 is an enlarged view showing the center portion of a pixel in FIG.5.

FIG. 7 is a plan view showing the configuration of a liquid crystaldisplay device according to Embodiment 3 of the present invention.

FIG. 8 is an enlarged view showing the center portion of a pixel in theliquid crystal display device shown in FIG. 7, in which (a) emphaticallyshows a gate layer and a source/drain layer, and (b) emphatically showsa fishbone-shaped pixel electrode.

FIG. 9 is a plan view showing the configuration of a liquid crystaldisplay device in a modified embodiment of Embodiment 3, and showing thecase of a smaller pixel size.

FIG. 10 is a plan view showing the configuration of a liquid crystaldisplay device according to Embodiment 4 of the present invention, inwhich (a) emphatically shows a gate layer and a source/drain layer, and(b) emphatically shows a BM.

FIG. 11 is a plan view showing the configuration of a liquid crystaldisplay device in a modified embodiment of Embodiment 4, in which (a)and (b) show different modified embodiments, respectively.

FIG. 12 is a plan view showing the configuration of a liquid crystaldisplay device according to Embodiment 5 of the present invention, inwhich (a) shows the configuration for operating in a CPA mode, and (b)shows the configuration for operating in an MVA mode.

FIG. 13 is an enlarged view showing the center portion of a pixel in theliquid crystal display device shown in FIG. 12( b).

FIG. 14 is a plan view showing the configuration of a liquid crystaldisplay device in a modified embodiment of Embodiment 5.

FIG. 15 is a plan view showing the configuration of a liquid crystaldisplay device according to Embodiment 6 of the present invention, inwhich (a) emphatically shows a gate layer and a source/drain layer, and(b) emphatically shows the components on a counter substrate.

FIG. 16 is an enlarged view showing the center portion of a pixel in theliquid crystal display device shown in FIG. 15.

FIG. 17 is a plan view showing the configuration of a liquid crystaldisplay device according to Embodiment 7 of the present invention.

DESCRIPTION OF EMBODIMENTS

A liquid crystal display device according to the embodiments of thepresent invention is a liquid crystal display device which includes acolumnar spacer in a pixel region and operates in a VA mode (forexample, a CPA mode or an MVA mode). In the liquid crystal displaydevice, a region of which the contribution to display is low in thevicinity of the columnar spacer and a region to be light-shielded suchas a TFT are covered with a BM, and a storage capacitor forming regionis formed so as to have a light-shielding property. In addition, acontact hole is disposed in this region, thereby preventing the displayquality from being degraded. These light-shielding regions are typicallydisposed in an appropriate manner without being dispersed in a regionincluding the center portion of the pixel, thereby improving an apertureratio. In the case of the operation in the CPA mode, the columnar spacerdisposed in the pixel region can be positively utilized as anorientation regulating structure of liquid crystal molecules.

The technique related to such a liquid crystal display device isdisclosed by the inventors of the present invention in InternationalPublication No. WO 2011/096390. FIG. 16 and other figures ofInternational Publication No. WO 2011/096390 show the configuration inwhich a columnar spacer is disposed in the center portion of a pixel,and the columnar spacer, a TFT, and a contact hole are integrallycovered with a BM. In this liquid crystal display device, however, astorage capacitor to be formed in the pixel region is not formed by anelectrode with light-shielding property, but formed by using atransparent electrode. International Publication No. WO 2011/096390 alsodiscloses the configuration in which the storage capacitor is formed byan electrode with light-shielding property, but in such a case, thestorage capacitor is formed not in the pixel region but by utilizing agap between pixels. In addition, a source bus line is provided along abackbone portion of a fishbone electrode (along a line for dividing thepixel region into two parts), and a TFT is disposed in the centerportion of the pixel. Such a configuration is described to be applied tothe case of a pixel size of approximately 100 μm×300 μm, for example.

On the other hand, in the embodiments of the present invention,typically, an electrode formed from the same material as that of a gatebus line and an electrode formed from the same material as that of asource bus line are used, thereby forming a storage capacitor with aninsulating film of the same material as that of the gate insulating filminterposed between the electrodes. With such a configuration, it isunnecessary to additionally provide a transparent electrode for forminga storage capacitor and an insulating film between the transparentelectrode and the pixel electrode, so as to be advantageous in theproduction process and the production cost. In the embodiments of thepresent invention, a storage capacitor portion formed by using amaterial with light-shielding property is arranged so as to overlap withthe contact hole, so that the alignment disorder region of liquidcrystal molecules occurring in the contact hole portion and around theportion can be efficiently light-shielded. In this configuration, it isnot necessary to ensure a margin in view of the displacement inlaminating substrates, as compared with the case where the alignmentdisorder region of the contact hole portion is light-shielded by the BM.As the margin for the displacement in laminating substrates, about 5 μmis required, for example. Accordingly, in the case of a smaller pixelsize (for example, 50 μm×150 μm), the configuration of the presentinvention is also preferable.

In addition, in the present invention, the above of a source bus line isnot covered with a transparent electrode for forming a storagecapacitor. Accordingly, the load of the source bus line is low, and thepresent invention is suitable for mobile equipment for which thereduction of power consumption is required.

Hereinafter, the embodiments of the present invention will be describedwith reference to the accompanying drawings, but the present inventionis not limited to these embodiments.

Embodiment 1

FIG. 1( a) and FIG. 1( b) show the configuration of a liquid crystaldisplay device 100 according to Embodiment 1 of the present invention.FIG. 1( a) mainly shows the components on a TFT substrate (an activematrix substrate) 110 in the liquid crystal display device 100. FIG. 1(b) mainly shows the components on a counter substrate 120. In the liquidcrystal display device 100, between the TFT substrate 110 and thecounter substrate 120, a vertical alignment type liquid crystal layerformed by using a liquid crystal material having negative dielectricanisotropy (Δ∈<0) is sandwiched. The orientation of liquid crystalmolecules is regulated so that the liquid crystal molecules have a tiltangle closer to 90° (for example, equal to or more then 85° and lessthan 90°) in no voltage application by a vertical alignment film (notshown) disposed on the side of the liquid crystal layer of respectivesubstrate. The liquid crystal display device 100 with theabove-described configuration operates in a VA mode. Although not shownin the figure, a polarizing plate is disposed on the outer side of eachof the TFT substrate 110 and the counter substrate 120, and a backlightunit is provided on the outer side of the TFT substrate 110. Betweeneach of the polarizing plates and the liquid crystal layer, a ¼wavelength plate may sometimes be disposed.

In the liquid crystal display device 100 of this embodiment, the size ofa pixel (dot) is set to be 50 μm×150 μm (the diagonal of about 4.7inches of VGA system). In this specification, the term “pixel (dot)”indicates the minimum unit of monochromatic display, and a pictureelement which can perform full-color display can be obtained by threedots of RGB (red, green, and blue), for example.

As shown in FIG. 1( a), on the TFT substrate 110, a plurality of gatebus lines 2 extending in an X direction (in a first direction) and aplurality of source bus lines 4 extending in a Y direction (in a seconddirection) are disposed so as to be orthogonal to each other. In thevicinity of the crossing point of the gate bus line 2 and the source busline 4, a TFT 10 as an active element is formed for each pixel.

The TFT 10 is constituted, as shown in FIG. 2( a), by a gate electrode10G formed integrally with the gate bus line 2, a source electrode 10Sformed integrally with the source bus line 4, a drain electrode 10Dwhich becomes electrically conductive with the source electrode 10S whenan ON voltage is applied to the gate electrode 10G, and the like. Ingeneral, between the source electrode 10S and the drain electrode 10D, asemiconductor layer is provided so as to be opposite to the gateelectrode 10G via a gate insulating film.

In addition, as shown in FIG. 1( a), the TFT substrate 110 includes astorage capacitor bus line (a Cs bus line) 6 and a storage capacitorelectrode (a Cs electrode) 8, and a storage capacitor counter electrode(a Cs counter electrode) 16 connected to the drain electrode 10D (shownin FIG. 2) of the TFT 10 and a pixel electrode 12. On the pixelelectrode 12, a vertical alignment film (not shown) for maintaining thepre-tilt angle of liquid crystal molecules to be closer to 90° (in novoltage application) is provided.

The storage capacitor counter electrode 16 is provided so as to beoverlapped with the storage capacitor electrode 8 in the same layer asthe source/drain layer of the TFT 10 via an insulating layer such as agate insulating film. The storage capacitor electrode 8 and the storagecapacitor counter electrode 16 are opposite to each other via theinsulating film (for example, a gate insulating film), therebyconstituting a storage capacitor portion 80 (see FIG. 2). The drainelectrode 10D of the TFT 10 and the pixel electrode 12 are electricallyconnected via a contact hole 14 provided in an interlayer insulatinglayer (not shown) located on the TFT 10. FIG. 1( a) also shows theposition of a columnar spacer 24 provided on the counter substrate 120.

As shown in FIG. 1( b), the counter substrate 120 includes a blackmatrix (BM) 20 having an opening portion 22 provided on a transparentsubstrate, a counter electrode (not shown), and the columnar space 24provided on the counter electrode. For performing color display, colorfilters 22R, 22G, and 22B of R (red), G (green), and B (blue), forexample, are provided in a region corresponding to the opening portion22. It is noted that an alternative configuration in which the colorfilters are provided on the side of the TFT substrate 110 (so-calledcolor filter on TFT) may be adopted. In addition, a vertical alignmentfilm is provided on the side of the liquid crystal layer of the countersubstrate 120.

The columnar spacer 24 has a function of maintaining the gap between theTFT substrate 110 and the counter substrate 120 (a cell gap). In thisembodiment, the columnar spacer 24 also has a function as a structurefor regulating the orientation of liquid crystal molecules, and onecolumnar spacer 24 is provided for each of all pixels. Thecross-sectional shape of the columnar spacer 24 (the projected shapeonto a substrate surface when viewed from a normal direction of thesubstrate surface) is not limited to a regular octagon which is shown inthe figure, but may be any other type of polygon, or may alternativelybe a circle, an ellipse, or the like. It is preferred that the columnarspacer 24 may have a frustum shape, and that the area of the upperbottom surface (on the side of the TFT substrate 110) may be smallerthan the area of the lower bottom surface (on the side of the countersubstrate 120). In other words, it is preferred that the angle formed bythe surface of the counter substrate 120 and the side face of thecolumnar spacer 24 may be smaller than 90 degrees.

As is seen from FIG. 1( a) and FIG. 1( b), in this embodiment, in eachpixel region Px, the columnar spacer 24 is provided substantially in thecenter position thereof. Due to the orientation regulating force of thecolumnar spacer 24, in each pixel, liquid crystal molecules are orientedradially around the columnar spacer 24 in the application of voltage. Inother words, the liquid crystal display device 100 of this embodimentoperates in the CPA mode.

In addition, the TFT 10, the storage capacitor electrode 8 and thestorage capacitor counter electrode 16 (a portion in which the storagecapacitor electrode 8 and the storage capacitor counter electrode 16 areoverlapped when viewed from the normal direction of the substratesurface is referred to as a storage capacitor portion 80), and thecontact hole 14 are collectively arranged so as to be proximate to eachother in the center portion of the pixel region. As described above, thecolumnar spacer 24 on the counter substrate 120 is also disposed in thecenter portion of the pixel region Px, and is partially overlapped withthe storage capacitor counter electrode 16. In such a configuration, aportion 20 x which is continuously formed in the BM 20 is overlappedwith all of the TFT 10/the Cs electrode (the storage capacitorelectrode) 8/the Cs counter electrode (the storage capacitor counterelectrode) 16/the contact hole 14/the columnar spacer 24 in the planview (when viewed from the normal direction of the substrate surface).

Hereinafter, a light-shielding region of the liquid crystal displaydevice 100 will be described. In the liquid crystal display device 100,the following light-shielding regions (a) to (d) are provided.

(a) a BM region required for light-shielding the columnar spacer 24: Itis preferred to light-shield the region up to the outside of 2 μm to 4μm (about 3.0 μm in this embodiment) from the columnar spacer 24, forexample, in view of the deviation of alignment and the variation of linewidth when the columnar spacer 24 is formed on the BM 20 of the countersubstrate 120. The diameter of the lower bottom surface of the columnarspacer 24 (the distance between opposite two sides in the case ofoctagon) is set to be about 15 μm.

(b) a BM region required for light-shielding the TFT 10: When a channelportion of the TFT 10 is irradiated with light, the characteristicchange (for example, the change in magnitude of leakage current in theOFF condition) occurs. Accordingly, it is preferred that the channelportion is light-shielded by the BM. For example, in the case where thecell gap is set to be 3 μm, in view of the existence of light incidentin the orthogonal direction with respect to the normal direction of thesubstrate surface and the occurrence of displacement in bonding thecounter substrate, it is necessary to provide a region of about 7 to 15μm from the channel region as the BM region (about 7.5 μm in thisembodiment). Especially, in the on vehicle use, the outdoor use, or thelike, since the device is used under the environment in which the lightfrom outside is easily incident in the orthogonal direction, it ispreferred that the BM region is ensured to be larger.

(c) Storage capacitor forming region: In this embodiment, an electrodewhich constitutes a storage capacitor has the light shielding property.The storage capacitor forming region (the storage capacitor portion) 80is a region which does not contribute to display in the case where thedisplay device is of a transmission type. A storage capacitor can bealternatively formed by providing a transparent electrode under thepixel electrode via an insulating film. However, a region correspondingto the thus-formed storage capacitor is not included in thelight-shielding storage capacitor forming region 80 described herein.

In the environment of outdoor use, light from outside may sometimes bereflected from the Cs electrode 8 or the Cs counter electrode 16,thereby causing color unevenness to occur. For this reason, it ispreferred that the BM 20 may be disposed in the storage capacitorforming region in view of the display quality.

(d) Contact hole region: For example, an interlayer insulating film (anacrylic photosensitive resin film or the like) of about 3 μm is disposedbetween the drain electrode (or the storage capacitor counter electrode)and the pixel electrode, and the pixel electrode is formed thereon. Withsuch a configuration, in the contact hole 14 (for example, a squareshape having a side of about 7.5 μm) and the surrounding portionthereof, light leakage may easily occur due to liquid crystal alignmentdisorder in the inclined portion of the interlayer insulating film. Inthis embodiment, the contact hole 14 is formed on the storage capacitorportion 80, so as to light-shield the alignment disorder region.

The above-mentioned regions (a) to (d) are considered to be regions ofwhich the contribution to display is low (or which do not contribute todisplay). That is, it is preferred that light from these regions may notbe observed, and the region is desired to be light-shielded by the BM orto have the light-shielding property.

The light-shielding storage capacitor portion 80 is formed in thefollowing manner, for example. First, in the step of providing a gatebus line and a gate electrode, by using the same material as that of thegate bus line or the like (e.g., an Al film, a Cu film, an Mo film, a Tifilm, a Cr film, or the like, or an alloy film thereof, or a multi-layermetal film (a Ti—Al—Ti film or an Mo—Al film), a storage capacitorstorage bus line and a storage capacitor electrode are formed. Next, agate insulating film is provided so as to cover the storage capacitorelectrode. Thereafter, in the step of forming a source bus line and adrain electrode, by using the same material as that of the source busline or the like (e.g., an Al film, a Cu film, an Mo film, a Ti film, aCr film, or the like, or an alloy film thereof, or a multi-layer metalfilm (an Mo—Al—Mo film or a Ti—Al film), a storage capacitor counterelectrode is formed so as to be opposite to the storage capacitorelectrode on the gate insulating film. A storage capacitor portion 80 isobtained by the storage capacitor electrode and the storage capacitorcounter electrode which are oppositely arranged via a gate insulatingfilm (for example, an SiNx film or the like having the thickness ofabout 0.3 to 0.7 μm).

In the above-described configuration, the light-shielding region ofwhich the contribution to display is low is put in the center portion ofthe pixel. Accordingly, it is possible to more efficiently perform thelight shielding, as compared with the case where these regions aredispersed. These regions are disposed so as to be proximate to eachother, it is possible to improve the aperture ratio of a pixel while theoccurrence of light leakage is suppressed and the contrast ratio isimproved.

As described above, FIG. 2 shows the center portion of the pixel regionof the TFT substrate 110 shown in FIG. 1 in an enlarged manner. FIG. 2also shows the position of the columnar spacer 24 provided on thecounter substrate 120. The final position of the columnar spacer 24 inthe TFT 10 is determined in the step of sticking the TFT substrate 110and the counter substrate 120 together.

In the counter substrate 120, a partial region of the BM 20 required forlight-shielding the TFT 10 is indicated as a region 20 a. A partialregion of the BM 20 which covers the columnar spacer 24 and thesurrounding thereof is indicated as a region 20 b. As is seen from thefigure, in this embodiment, these regions 20 a and 20 b overlap eachother. This does not mean that these regions are separately providedactually so as to overlap each other, but means that the respectiveregions 20 a and 20 b defined in the BM 20 have the above-describedoverlap relationship.

As is seen from the figure, in this embodiment, the storage capacitorportion 80 and the region 20 b are arranged to overlap each other. Suchan arrangement is realized by providing the storage capacitor portion 80in the vicinity of the TFT 10 and providing the columnar spacer 24 inthe position corresponding to the storage capacitor portion 80 in thecounter substrate 120, and by locating the BM 20 so as to cover at leastthe entire of the columnar spacer 24 and the entire of the TFT 10.

In addition, a BM 20 c on the source bus line 4 shown in FIG. 2( b) isprovided for the purpose of avoiding colors from mixing when stickingdisplacement is caused between the TFT substrate 110 and the countersubstrate 120. The provision of the BM 20 c additionally provides thefollowing advantage. Specifically, in a portion away from the columnarspacer 24 as the orientation regulating structure (an end portion of thepixel region), the response of liquid crystal is inferior, so thatafterimage may easily occur. Accordingly, the covering of the portionwith the BM 20 c also provides the countermeasure for afterimage. Inthis embodiment, in order to form the BM pattern with high yield, the BM20 c on the source bus line and a BM integral portion 20 x including theBM 20 a and the BM 20 b of the region (a) and the region (b) arecontinuously (integrally) formed.

In this embodiment, on the counter substrate 120, opening portions 22disposed in upper and lower positions with the BM integral portion 20 xsandwiched therebetween for one pixel region Px (i.e., portions whichare not covered with the BM 20, and in which color filters are located)are provided. A portion in which the opening portion 22 and the pixelelectrode 12 overlap each other is defined as a display area in onepixel. These display areas disposed in the upper and lower positions ofthe BM integral portion 20 x are formed so as to have substantially thesame size. The columnar spacer 24 is disposed substantially in thecenter portion of the pixel electrode 12. With such a configuration, theviewing characteristics in the vertical direction in the figure can bemade uniform.

As shown in the figure, the contact hole 14 is also disposed in thepixel center portion. In this embodiment, the position of the columnarspacer 24 and the position of the contact hole 14 overlap each other. Insuch an arrangement, preferably, the size of the contact hole 14 is nottoo large with respect to the size of the columnar spacer 24, but ispreferably smaller than the size of the columnar spacer 24. If the sizeof the contact hole 14 is too large, the columnar spacer 24 is falleninto the inside of the contact hole 14, so that the columnar spacer 24may not function as the spacer for maintaining the cell gap. In thisembodiment, the contact hole 14 is set to have a substantially squareshape in section having the size of 7.5 μm×7.5 μm (the shape of thecontact hole in the substrate plane). The sectional shape of the lowerbottom surface of the columnar spacer 24 functioning as the orientationregulating structure/the spacer is set to be a regular octagon in whichthe distance between opposite two sides is 15 μm.

Next, with reference to FIG. 3( a) and FIG. 3( b), the configuration ofa liquid crystal display device 100A as a modified example of Embodiment1 will be described.

As shown in FIG. 3( a) and FIG. 3( b), in the liquid crystal displaydevice 100A, a BM 20A is disposed so as to selectively and integrallycover a TFT 10 and a columnar spacer 24. Unlike the configuration shownin FIG. 1( a) and FIG. 1( b), the BM 20A does not cover the entire of astorage capacitor portion 80. The BM 20A only partially covers a contacthole 14. In other words, as compared with the liquid crystal displaydevice 100 shown in FIG. 1 and FIG. 2, the area of BM is reduced in theliquid crystal display device 100A.

Also in the liquid crystal display device 100A in this modifiedembodiment, it is possible to obtain display with high aperture ratio(high luminance) and high contrast ratio by commonly providing theabove-described regions (a) to (d) of which the contribution to displayis low (or which do not contribute to display) or by disposing themproximately to each other. As shown as an additional opening portion 22a in FIG. 3( b), the opening portion of the pixel is increased as awhole, so that it is possible to perform display with higher luminance.It is noted that since the storage capacitor portion 80 has thelight-shielding property as described above, the display quality willnot be degraded due to the alignment disorder caused in the contact hole14 and the surrounding portion thereof.

FIG. 4 shows the configuration in which the liquid crystal displaydevice shown in FIG. 1 (the VGA system having the pixel size (dot pitch)of 50 μm×150 μm) is applied to a high-definition liquid crystal displaydevice having a smaller pixel size. The configuration shown in FIG. 4 isthe case applied to the wide XGA system having the pixel size of 30μm×90 μm (1280×RGB×800 pixels, and the diagonal of about 5.35 inches).

In this case, on the TFT substrate 110, the TFT 10, the storagecapacitor portion 80, and the contact hole 14 are disposed proximatelyto each other, and the columnar spacer 24 provided on the countersubstrate 120 is formed in a position so as to overlap with them, sothat it is possible to provide a BM which can integrally cover entirelythe region which does not contribute to display and preferably belight-shielded. Accordingly, the degradation of contrast ratio caused bylight leakage can be prevented, and the aperture ratio can be improved.

In the above-described embodiment, the configuration in which thecolumnar spacer 24 is provided on the side of the counter substrate 120is described. Alternatively, the columnar spacer 24 may be provided onthe side of the TFT substrate 110.

Embodiment 2

FIG. 5( a) and FIG. 5( b) show a liquid crystal display device 102 ofEmbodiment 2. FIG. 6 shows the center portion of a pixel region in FIG.5( a) and FIG. 5( b) in an enlarged manner. The same components as thosein Embodiment 1 are designated by the same reference numerals, and thedescriptions thereof are omitted.

In this embodiment, on a counter substrate 122, a columnar spacer 24 a(a pattern of octagon shown in FIG. 5 and FIG. 6), and a sub columnarspacer 24 b (a pattern of circle shown in FIG. 5 and FIG. 6) which isformed to be lower than the columnar spacer 24 a are provided.

In the liquid crystal display device 100 of Embodiment 1 shown in FIG.1, one kind of columnar spacer 24 is disposed for each of all pixels. InEmbodiment 2, in part of the pixel, the sub columnar spacer 24 b isdisposed instead of the columnar spacer 24 a. The sub columnar spacer 24b is formed on a BM and a counter electrode of the counter substrate122, similarly to the columnar spacer 24 a. However, as compared withthe columnar spacer 24 a, the height of the sub columnar spacer 24 b isshorter. Therefore, in such cases where any pressure is applied from theoutside, the top end portion thereof comes into contact with the TFTsubstrate 112. For example, the height of the columnar spacer 24 a isset to be 3.0±0.2 μm, and the height of the sub columnar spacer 24 b isset to be 2.7±0.2 μm.

In addition to the sub columnar spacer 24 b, a projection (hereinafterreferred to as “a rivet”) which has a height shorter than the subcolumnar spacer 24 b may be included. The rivet has only the orientationregulating function, and does not substantially contribute to themaintaining of the cell thickness. The height of the rivet is set to be,for example, 0.8±0.2 μm.

Alternatively, the sub columnar spacer 24 b is not provided, but onlythe columnar spacer 24 a and the rivet may be disposed on the countersubstrate 122. The shapes of the columnar spacer 24 a, the sub columnarspacer 24 b, and the rivet in plan view may be the same, or may bedifferent. Alternatively, the diameters of the columnar spacer 24 a, thesub columnar spacer 24 b, and the rivet in plan view may be the same, ormay be different.

The dielectric constants of the sub columnar spacer 24 b and the rivetare preferred to be smaller than that of liquid crystal. The reason isthat the tilt direction of liquid crystal molecules promoted inaccordance with the shape of the side face of the spacer or the rivetand the direction in which the electric field causes the liquid crystalto tilt will not be opposite to each other.

As described above, some of the columnar spacers 24 a may be replaced bythe sub columnar spacers 24 b or the rivets having shorter heights,thereby reducing the occurrence of air bubbles in the liquid crystallayer when the temperature changes.

For example, in the case where the liquid crystal panel is stored at alow temperature (e.g. −30° C.), vacuum bubbles may sometimes occurbecause of the difference between the contraction rate of liquid crystaland the contraction rate of other members (in this case, the columnarspacer). Particularly in the case of the high-definition liquid crystaldisplay device, if the columnar spacers 24 a are disposed for everypixel, the number of columnar spacers to be provided is equal to orlarger than the required number for maintaining the cell thickness. As aresult, the risk of bubble occurrence may undesirably be increased. Insuch a case, some of the columnar spacers 24 a may be changed to therivets or the sub columnar spacers 24 b having smaller volumes, therebyadequately adjusting the arrangement density.

Especially in the small-sized and high-definition liquid crystal displaydevice, it may sometimes be sufficient that the number of spacersrequired for maintaining the cell gap be smaller than the number ofpixels. The configuration of this embodiment can suitably be used forsuch a case.

As for the arranging formation of the columnar spacers 24 a and the subcolumnar spacers 24 b, for example, the columnar spacers 24 a may bedisposed for all of the B (blue) pixels, and the sub columnar spacers 24b may be disposed for other pixels (the R (red) pixels and the G (green)pixels). Alternatively, for example, the columnar spacers 24 a may bedisposed for four B pixels among twenty seven pixels, the sub columnarspacers 24 b may be disposed for five B pixels among the twenty sevenpixels, and the rivets may be disposed for eighteen pixels of the othercolors (R and G). Since the B pixels have low transmittance, thedegradation of display quality caused by the alignment disorder is hardto be observed even if the columnar spacers 24 a are disposed.Accordingly, it is preferred that the columnar spacers 24 a may bedisposed for the B pixels.

The sub columnar spacers 24 b are, for example, suitably used as cellthickness maintaining members when a touch panel or the like is providedon the surface of a liquid crystal panel. Alternatively, if the subcolumnar spacers 24 b and the rivets are used instead of the columnarspacers 24 a, in the case where the liquid crystal injection isperformed by ODF (One Drop Filling) in the manufacture of liquid crystalcell, the dropped liquid crystal can be advantageously dispersed moreuniformly.

In the configuration with smaller dot pitch as shown in FIG. 4, theconfiguration in which the columnar spacers and rivets having differentheights as described in Embodiment 2 can be applied.

As described above, in the case where the columnar spacers 24 a are notprovided for all of the pixels, it is sufficient to arrange the columnarspacers 24 a so that the arrangement density is uniform over the entiredisplay area of the liquid crystal panel. With such a configuration, therivets or the like for orientation regulation disposed instead of thecolumnar spacers 24 a can have any arbitrary shape which is moresuitable for orientation regulation.

Embodiment 3

FIG. 7 shows a liquid crystal display device 103 in Embodiment 3. Theliquid crystal display device 103 is different from the liquid crystaldisplay device 100 of Embodiment 1 in that the liquid crystal displaydevice 103 includes a fishbone-shaped pixel electrode 12F on a TFTsubstrate 113. The same components as those in Embodiment 1 or 2 aredesignated by the same reference numerals, and the descriptions thereofare omitted.

Such a liquid crystal display device including the fishbone-shaped pixelelectrode is described, for example, in International Publication No. WO2011/096390 by the applicant of the present invention, the entirecontents of which are incorporated by reference herein.

In this embodiment, in order to improve the response speed of liquidcrystal orientation in voltage application, PSA (Polymer SustainedAlignment) technique may be used. The PSA technique is a technique inwhich an orientation maintaining layer for applying pre-tilt to liquidcrystal in no voltage application is formed. The orientation maintaininglayer is formed as a polymer layer in the following manner. After aliquid crystal cell is formed, a photo-polymerizable monomer which ispreviously mixed in a liquid crystal material is photo-polymerizedtypically in the condition where a voltage is applied across the liquidcrystal layer. By the orientation maintaining layer, the liquid crystalin no voltage application can be maintained (memorized) to have apre-tilt angle in a direction slightly inclined (e.g., 2° to 3°) fromthe direction perpendicular to the substrate surface and the orientationdirection.

The PSA technique can be applied to Embodiment 1 or the like in additionto the combination with the fishbone-shaped pixel electrode, therebyattaining the effect of the increase in response speed.

FIG. 8( a) and FIG. 8( b) show the vicinity of the center portion of onepixel region in FIG. 7 in an enlarged manner. FIG. 8( a) emphaticallyshows a gate layer including a storage capacitor electrode and asource/drain layer including a storage capacitor counter electrode. FIG.8( b) emphatically shows a fishbone-shaped pixel electrode 12F. In thisspecification, the gate layer includes a gate bus line, a gateelectrode, a storage capacitor bus line, and a storage capacitorelectrode. The source/drain layer includes a source bus line, a sourceelectrode, a drain electrode, and a storage capacitor counter electrode.

In the fishbone-shaped pixel electrode 12F, for example, as shown in thefigure, branch minute electrodes having a width (w1) of about 3.4 μm aredisposed with an interval (w2) of about 3.2 μm, thereby forming a slit12S. The fishbone-shaped pixel electrode 12F has a backbone portion 12B(a stem portion) extending in the center of the pixel region in parallelto the source bus line 4, and a plurality of minute electrodes extendingin directions which are different from each other are connected to thebackbone portion 12B. The backbone portion 12B has, for example, a width(w3) of about 5 μm. As described above, in this embodiment, minuteelectrodes (minute slits) are formed so that one pixel is roughlydivided into four orientation regions (domains) A1 to A4.

When a voltage is applied between the pixel electrode 12F and thecounter electrode, in each domain, liquid crystal molecules 50 areoriented so as to be parallel to the direction in which the slit 12Sextends and so that upper end portions of the liquid crystal molecules50 (end portions on the side of a common electrode) are tilted towardthe inside of the pixel.

In this embodiment, the columnar spacer 24 has a planar shape of regularoctagon or the like with four sides perpendicular to respectiveorientation directions (azimuth angles of 45°, 135°, 225°, 315°) ofliquid crystal molecules in the respective domains A1 to A4. Inaddition, the columnar spacer 24 has a frustum shape in which an angleformed by the surface of the counter substrate and the side face of thecolumnar spacer 24 is smaller than 90 degrees. Since a verticalalignment film is also formed on the side face of the columnar spacer24, the orientation regulating force to the liquid crystal molecules 50works by means of the columnar spacer 24. The direction of theorientation regulation (the direction in which the liquid crystalmolecules 50 are to be tilted) is the direction perpendicular to theside face of the columnar spacer 24.

As shown in FIG. 8( a), the liquid crystal molecules 50 in the domainsA1 to A4 around the columnar spacer 24 are intended to be orientedtoward the columnar spacer 24, but the side face of the columnar spacer24 has a face perpendicular to the orientation direction. Thus, thedirection of orientation regulation by the columnar spacer 24 agreeswith the direction of orientation regulation by the domains A1 to A4 (orthe directions are closer to each other). In addition, the orientationdirection of a boundary region between the domains A1 to A4 (i.e. theliquid crystal molecules on the backbone portion 12B) in which theorientation direction of the liquid crystal molecules 50 is unstable canbe oriented toward the columnar spacer 24. Accordingly, it is possibleto obtain display with good transmittance, contrast ratio, or viewingangle characteristics in which the alignment disorder hardly occurs. Inaddition, a defect in which transmittances of respective domains aredifferent is reduced, so that it is possible to provide high qualitydisplay in which the occurrence of roughness or the like is avoided. Asdescribed above, in the case where a plurality of domains are definedaround the center of the pixel region by the fishbone-shaped pixelelectrode 12F, a columnar spacer 24 is preferably disposed in the centerof the pixel region, whereby the alignment disorder is hard to occur.

Preferably, the orientation directions of liquid crystal molecules inthe respective domains A1 to A4 form an angle of 45° with respect to thepolarizing axes (the three-o'clock to nine-o'clock direction and thetwelve-o'clock to six-o'clock direction) of the polarizing platedisposed on the outside of the liquid crystal panel.

FIG. 9 shows the case in which the present invention is applied to thewide XGA system (1280×RGB×800 pixels, and the diagonal of about 5.35inches) having the pixel size of 30 μm×90 μm. In accordance with theminimum line width defined by the limits in the production process orthe like, the shapes of the pixel electrode and the storage capacitorportion are different from those in the liquid crystal display device103 shown in FIG. 7 and FIG. 8, but the display apparatus can operatesimilarly to the liquid crystal display device 103.

As described above, if the orientation direction of liquid crystalmolecules promoted by the slits of the pixel electrode is similar to theorientation direction of liquid crystal molecules promoted by thecolumnar spacer, as in this embodiment, the liquid crystal molecules canbe more surely maintained in the desired orientation, when the PSAprocessing is performed, thereby suppressing the occurrence of roughnessand irregularity. In addition, the response speed can be improved, sothat the abnormal alignment caused when the liquid crystal panel surfaceis pressed by a finger or the like can be returned to the normalalignment earlier. For example, it is suitable for the case where thetouch panel or the like is set on the surface of the liquid crystalpanel.

Embodiment 4

FIG. 10( a) and FIG. 10( b) show a liquid crystal display device 104 ofEmbodiment 4. FIG. 10( a) emphatically shows a gate layer and asource/drain layer, and FIG. 10( b) emphatically shows a BM 20. InEmbodiment 4, in the configuration utilizing the fishbone-shaped pixelelectrode 12F in Embodiment 3, an additional storage capacitor portion82 is formed in a region corresponding to the backbone portion 12B ofthe fishbone-shaped pixel electrode 12F. The same components as those inEmbodiments 1 to 3 are designated by the same reference numerals, andthe descriptions thereof are omitted.

In this embodiment, a Cs bus line 6A is located in a space between thefishbone-shaped pixel electrodes 12F which are vertically adjacent toeach other in the figure, and the Cs capacitor portion 82 isadditionally disposed in the backbone portion 12B of the fishbone-shapedpixel electrode 12F. The Cs capacitor portion 82 is constituted by a Csline (a Cs electrode) extending from the Cs bus line 6A, an insulatingfilm provided thereon, and a Cs counter electrode provided thereon as anadditional portion extending from the Cs counter electrode 16 shown inEmbodiment 3 or the like.

To the Cs bus line 6A, via the Cs line which overlaps with the backboneportion 12B (the Cs electrode which constitutes the above-mentioned Cscapacitor portion 82), a storage capacitor electrode 8 provided in thepixel center portion (the region in which the columnar spacer 24 isdisposed) is connected. Similarly to Embodiment 3, the storage capacitorportion 80 positioned in the pixel center is also formed.

The backbone portion 12B of the fishbone-shaped pixel electrode 12F ispositioned on the boundary between the regions (domains) havingdifferent liquid crystal orientations, and is the portion of which thecontribution to display is low. For example, even when a voltage ofwhite display is applied, the boundary portion often becomes a darkline. In addition, the orientation regulating force by the slits isweak, so that the alignment disorder may easily occur. This embodimenthas the configuration in which the Cs capacitor portion is added to theregion, so that the storage capacitor can be increased while thedegradation of display quality is suppressed.

The space portion between fishbone-shaped pixel electrodes 12F which arevertically adjacent to each other in the figure is also a portion ofwhich the contribution to display is low, so that the Cs bus line 6A isdisposed in this portion. As described above, the Cs capacitor portion82 is formed in the region Cs of which the contribution to display islow, so that the degradation of display quality can be prevented. By theprovision of the Cs capacitor portion 82, even when the size of the Cscapacitor portion 80 in the center portion of the pixel electrode ismade smaller, it is possible to ensure sufficient Cs capacitance.

FIG. 11( a) shows a liquid crystal display device 104A in a modifiedembodiment of Embodiment 4. In this modified embodiment, the additionalCs capacitor portion 84 is also formed on the lower side with thecolumnar spacer 24 sandwiched therebetween. With such a configuration,Cs capacitance can be increased. Alternatively, the aperture ratio canbe improved while the Cs capacitance is maintained to the same extent.

FIG. 11( b) shows a liquid crystal display device 104B in anothermodified embodiment of Embodiment 4. In this another modifiedembodiment, the additional Cs capacitor 86 is also formed on the Cs busline 6A. With such a configuration, the Cs capacitance can be increased.Alternatively, the aperture ratio can be improved while the Cscapacitance is maintained to the same extent.

In Embodiment 3 shown in FIG. 8( a), the distance L0 from the edge ofthe pixel electrode 12 to the Cs bus line 6 (corresponding to the sizeof the display area) is set to be 46.25 μm, for example. On the otherhand, in the liquid crystal display device 104 shown in FIG. 10( a) andFIG. 10( b), the distance L1 from the edge of the pixel electrode 12 tothe Cs electrode 8 can be set to be 48.25 μm. In the liquid crystaldisplay device 104A shown in FIG. 11( a), the distance L2 from the edgeof the pixel electrode 12 to the Cs electrode 8 can be set to be 50.25μm. In the liquid crystal display device 104B shown in FIG. 11( b), thedistance L3 from the Cs bus line 6A to the Cs electrode 8 can be set tobe 49.5 μm.

According to this embodiment, while the Cs capacitance can be ensured tothe same extent as in Embodiment 3, the region which contributes todisplay in one pixel can be increased. The region for which theorientation regulation is weak and of which the contribution to displayis low, such as the region between pixels vertically adjacent to eachother is light-shielded, so that display defect such as that roughnessor the like is visually recognized can be suppressed. Also by thecolumnar spacer in this embodiment, similarly to Embodiment 3, theeffects such as the improvement in response speed can be attained byutilizing the orientation regulating force of the columnar spacer.

Embodiment 5

FIG. 12( a) shows a liquid crystal display device 105 in Embodiment 5.FIG. 12( b) shows a liquid crystal display device 105A in a modifiedembodiment of Embodiment 5 in which a fishbone-shaped electrode is used.FIG. 13 shows the center portion of a pixel region in the liquid crystaldisplay device 105A shown in FIG. 12( b) in an enlarged manner. The samecomponents as those in Embodiments 1 to 4 are designated by the samereference numerals, and the descriptions thereof are omitted.

This embodiment describes the configuration in which Embodiment 1 andEmbodiment 3 are applied to a pixel having substantially square shape.For example, this embodiment is suitable for the case where colorfilters of four colors (RGB+White, RGB+Yellow, or the like) are used, orthe case of monochrome display with no color filters. In thisembodiment, the pixel size is set to be, for example, 75 μm×75 μm.

FIG. 12( a) illustrates the configuration in which four color pixels ofRGB+White are arranged, but the arrangement of the respective colors isnot limited to the shown one.

In this embodiment, as the result of the correspondence with squarepixels, the contact hole and the columnar spacer do not overlap witheach other. These are separately disposed with a distance, and thedistance W4 (see FIG. 13) is set to be 5 μm, for example.

A BM 20 d (the width thereof is 5.5 μm in this embodiment) is providedalso in the space between pixel electrodes vertically adjacent to eachother in the figure. This is provided for the purpose of preventing thecolors from being mixed in the vertical direction in the case of fourcolor filters. In the case of no color filters, it is unnecessary toprovide the BM 20 d.

As a further modified example, FIG. 14 shows a liquid crystal displaydevice 105B in the case where the modified embodiment of Embodiment 4shown in FIG. 11( b) is adapted to square pixels. In a positioncorresponding to the gap portion, BM 20 d, which is disposed betweenpixel electrodes vertically adjacent to each other in the case of fourcolor filters, an additional Cs capacitor portion 86 is provided. As aresult, the aperture ratio can be improved while the storage capacitanceis adequately obtained.

Embodiment 6

FIG. 15( a) and FIG. 15( b) show a liquid crystal display device 106 inEmbodiment 6. FIG. 16 shows a pixel region in the liquid crystal displaydevice 106 shown in FIG. 15 in an enlarged manner. The same componentsas those in Embodiments 1 to 5 are designated by the same referencenumerals, and the descriptions thereof are omitted.

The liquid crystal display device 106 includes, in the pixel region, inaddition to a main pixel electrode 12F1 directly connected to a TFT 10,a sub pixel electrode 12F2 connected to the TFT 10 via a couplingcapacitor (not directly connected electrically, and in a floatingcondition). To the main pixel electrode 12F1, a predetermined voltage isapplied based on a signal from a source bus line 4. On the other hand,to the sub pixel electrode 12F2 connected via the coupling capacitor, avoltage different from the voltage applied to the main pixel electrode12F1 is applied. Accordingly, in one pixel region, two pixel regions Px1and Px2 having different orientation conditions are provided.

The above-described configuration in which a plurality of pixel regionsPx1 and Px2 with different orientations are provided in one pixel isreferred to as a multi-pixel type, and is known as a technique forimproving the viewing angle characteristics. The size of a pixelincluding the pixel regions Px1 and Px2 is 75 μm×225 μm. As shown in thefigure, both of the pixel electrodes 12F1 and 12F2 are of the fishbonetype which is similar to Embodiment 3.

In the configuration of this embodiment, in the main pixel region Px1,the same configurations as descried in Embodiments 1 to 4 can beadopted. A columnar spacer 24 is provided in the center portion of amain pixel electrode 12F1, and a rivet 24 c is provided in the centerportion of a sub pixel electrode 12F2. The rivet 24 c regulates theorientation of liquid crystal molecules 50 in the sub pixel region Px2.

The coupling capacitor of the sub pixel electrode 12F2 is formed in anoverlap portion (the cross shape) between the backbone portion of thesub pixel electrode 12F2 and the extended portion 18 of the drainelectrode of the TFT with an insulating film sandwiched therebetween.Two Cs bus lines 6A and 6B are disposed between adjacent gate bus lines2, and they are disposed, respectively, in spaces between the main pixelelectrodes 12F1 and the sub pixel electrodes 12F2 vertically adjacent toeach other. In this embodiment, similarly to the configuration shown inFIG. 11( b) and the like, the Cs capacitor portion 86 is also formed onthe Cs bus line.

Such a multi-pixel configuration is suitably utilized, for example, intelevision, digital signage, or the like. The display quality can beimproved especially when viewed from the diagonal direction.

Embodiment 7

FIG. 17 shows a liquid crystal display device 107 in Embodiment 7. Thisembodiment is different from Embodiment 3 in the arrangement of contactholes 14A and 14B. In this embodiment, the positional relationship ofthe contact holes 14A and 14B with respect to the columnar spacer 24 isdifferent between pixels. In this embodiment, there are two kinds ofpositions of the contact holes 14A and 14B. The same components as thosein Embodiment 1 to 6 are designated by the same reference numerals, andthe descriptions thereof are omitted.

In the step of sticking the counter substrate to the TFT substrate,there may occur any positional deviation between them (for example,about 5 μm). When a columnar spacer and a sub columnar spacer are to beformed on the counter substrate, any positional deviation with respectto the counter electrode by several micrometers may occur.

In the case where the positional relationships between the columnarspacers and the contact holes are the same in all of the pixels, if thepositional deviation occurs in one specific direction, the contact areaof the columnar spacer with the TFT substrate is easily varied largely.On the other hand, if a plurality of positional relationships areprovided as described above, it is possible to prevent the contact areafrom being varied between products produced in mass production. When theplurality of positional relationships are set, it is desired that therespective numbers of contact holes 14A and 14B having differentpositional relationships are equally set in the display area. Inaddition, it is desired that the contact holes 14A and 14B may beprovided in such a manner that the respective contact holes 14A and 14Bhaving predetermined positional relationships be uniformly disposed inthe display area.

Herein, the configuration in which the positions of the contact holesare changed in the modified embodiment of Embodiment 3 is described, butthe configuration can be applied in the other embodiments.

The embodiments of the prevent invention are described above, but othervarious kinds of configurations can be adopted. For example, the presentinvention can be applied to the case where pixels are arranged in adelta array. Alternatively, the present invention can be applied to asemi-transmission type liquid crystal display device by providing areflective electrode around a pixel electrode.

INDUSTRIAL APPLICABILITY

The present invention can be widely used in liquid crystal displaydevices of various applications. The present invention can be suitablyutilized as a small-sized and high-definition liquid crystal displaydevice of VA mode which is provided in an electronic book, a smartphone, or the like, for example.

REFERENCE SIGNS LIST

-   -   100 Liquid crystal display device    -   110 TFT substrate    -   120 Counter substrate    -   2 Gate bus line    -   4 Source bus line    -   6 Storage capacitor bus line    -   8 Storage capacitor electrode    -   10 TFT    -   12 Pixel electrode    -   14 Contact hole    -   16 Storage capacitor counter electrode    -   20 Black matrix    -   22 Opening portion    -   24 Columnar spacer    -   80 Storage capacitor forming region (Storage capacitor portion)    -   Px Pixel region

The invention claimed is:
 1. A liquid crystal display device comprising:a thin film transistor (TFT) substrate, a counter substrate, and avertical alignment type liquid crystal layer sandwiched between the TFTsubstrate and the counter substrate, wherein the TFT substrate includes:a first substrate; a gate bus line provided so as to extend along afirst direction on the first substrate; a source bus line provided so asto extend along a second direction which intersects the first directionon the first substrate; a TFT provided in the vicinity of theintersecting portion of the gate bus line and the source bus line; aninterlayer insulating layer which covers the TFT; a pixel electrodeelectrically connected to the TFT via a contact hole formed in theinterlayer insulating layer; a storage capacitor bus line provided onthe first substrate and a storage capacitor electrode connected to thestorage capacitor bus line; and a storage capacitor counter electrodehaving a light-shielding property electrically connected to the TFT andthe pixel electrode, the storage capacitor counter electrodeconstituting a storage capacitor portion together with the storagecapacitor electrode with an insulating layer interposed therebetween,and the counter substrate includes: a second substrate; and a counterelectrode provided on the second substrate, and wherein the liquidcrystal display device further comprises a black matrix having alight-shielding property provided on the first substrate or on thesecond substrate, and a columnar spacer provided between the TFTsubstrate and the counter substrate, the columnar spacer being disposedin a center portion of a pixel region corresponding to the pixelelectrode so as to at least partially overlap with the storage capacitorcounter electrode, the contact hole being provided so as to overlap withthe storage capacitor counter electrode, and the black matrix includinga portion which integrally covers the TFT and the columnar spacer. 2.The liquid crystal display device of claim 1, wherein the source busline is disposed so as to extend along a peripheral portion of the pixelregion, and the TFT is disposed in the vicinity of the peripheralportion of the pixel region.
 3. The liquid crystal display device ofclaim 1, wherein the columnar spacer is disposed so as to at leastpartially overlap with the pixel electrode.
 4. The liquid crystaldisplay device of claim 1, wherein the black matrix is disposed so as toat least partially overlap with the storage capacitor counter electrode.5. The liquid crystal display device of claim 1, wherein the blackmatrix includes a first BM portion for light-shielding the TFT and asecond BM portion for light-shielding the columnar spacer, the first BMportion overlapping with the second BM portion.
 6. The liquid crystaldisplay device of claim 1, wherein the contact hole and the columnarspacer are disposed so as to at least partially overlap with each other.7. The liquid crystal display device of claim 1, wherein the orientationof liquid crystal molecules of the liquid crystal layer is radiallyregulated by the columnar spacer when a voltage is applied.
 8. Theliquid crystal display device of claim 1, wherein the pixel electrodeincludes a plurality of first minute electrodes extending in a thirddirection, a plurality of second minute electrodes extending in a fourthdirection, a plurality of third minute electrodes extending in a fifthdirection, and a plurality of fourth minute electrodes extending in asixth direction, the third direction, the fourth direction, the fifthdirection, and the sixth direction being mutually different.
 9. Theliquid crystal display device of claim 8, wherein the pixel electrodeincludes a backbone portion formed in a boundary portion of the first tofourth minute electrodes, and an additional storage capacitor is formedin a region corresponding to the backbone portion.
 10. The liquidcrystal display device of claim 1, wherein the liquid crystal displaydevice comprises a plurality of pixel regions, and a projectionstructure which is lower than the columnar spacer is provided in thecenter portion of a pixel region which is different from the pixelregion in which the columnar spacer is provided among the plurality ofpixel regions.
 11. The liquid crystal display device of claim 1, furthercomprising a sub pixel electrode disposed adjacently to the pixelelectrode, and connected to the TFT via a capacitance coupling.
 12. Theliquid crystal display device of claim 1, wherein the liquid crystaldisplay device comprises a plurality of pixel regions, and the positionof the contact hole with respect to the columnar spacer is differentbetween at least two pixel regions among the plurality of pixel regions.